Bratislava-77 Avian Sarcoma Virus (B77-ASV) will be produced in tissue culture in roller bottles and highly concentrated for intracerebral inoculation of neonatal inbred Fischer rats to induce experimental brain tumors (gliomas and sarcomas). Virus-cell relationships of the tumors will be examined in terms of morphologically and biologically detectable replicating virus and viral antigens. Induction of possible candidate human tumor virus will be attempted in tissue culture. Localization of purified, radioantibodies in experimental glioma bearing rats will be refined. The role of cellular immunity in relationship to pathogenesis of developing B77-ASV- induced experimental gliomas will be studied in vitro with migration inhibition factor and cytotoxicity tests.